1. Field of the Invention
The present invention relates to a rotary compressor, and more particularly, to a rotary compressor which can attenuate a noise generated in operation of the rotary compressor and improve lubrication.
2. Background of the Related Art
The compressor for compressing air or gas to a required pressure is used in an air conditioner or the like for compressing a refrigerant gas to a required pressure.
A related art rotary compressor will be explained with reference to FIGS. 1 and 2.
The related art rotary compressor is provided with a hermetic case 1 having a suction pipe 16 for drawing refrigerant and a discharge pipe 5 for discharging the compressed refrigerant, both connected thereto respectively, a driving unit 6 in the case 1 for providing a rotating force, and a compression unit 10 for compressing the refrigerant. The driving unit 6 has a stator 2 and a rotor 3 of a motor disposed at an upper portion in the case 1. The rotor 3 is coupled to a shaft 4 for transmission of the rotating power to the compression unit 10. The rotor 3 has an eccentric portion 4a at a lower portion thereof. The compression unit 10 has a compression chamber `C` enclosed by a cylinder 11 forming a wall of the compression chamber `C`, and a main bearing 14 and a supplementary bearing 15 mounted at an upper side and a lower side of the compression chamber `C` respectively. The compression chamber `C` has the suction pipe 16 connected thereto for receiving refrigerant from outside of the compression chamber `C`. The cylinder 11 and the main bearing 14 have a discharge opening 11a and a discharge passage 14b formed therein respectively for discharging refrigerant, which discharge passage 14b is opened/closed by a valve(not shown). In the meantime, the eccentric portion 4a of the shaft is mounted in the compression chamber `C`, i.e., inside of the cylinder 11. There is a roller 12 fitted to an outside of the eccentric portion 4a for making a compression action as the eccentric portion 4a keeps making contact with an inside surface of the cylinder 11 following rotation of the eccentric portion 4a. And, there is a vane 13 mounted in the cylinder 11 to be always in contact with an outside of the roller 12 biased by a spring for dividing the compression chamber `C` into a high pressure portion and a low pressure portion. There is a muffler 20 above the main bearing 14 for attenuation of noise, which has a muffler discharge opening 21 for discharging refrigerant flowed into the muffler 20 to an outside of the muffler 20.
The muffler will be explained with reference to FIGS. 3A-3B.
The muffler 20 in a form of a cap has a boss hole 22 at a center for passing a boss portion 14a of the main bearing 14, and recessed bolt fixing parts 23 in an outer circumference thereof. The muffler 20 has a muffler discharge opening 21 formed at a position between an inside diameter and an outside diameter for discharging the compressed gas flowed into the muffler 20.
In the meantime, lubrication oil is applied to various components of the compressor for smooth operation. That is, a pump(not shown) draws lubricating oil stored on a bottom of the case 1 and supplies to between the main bearing 14 or the supplementary bearing 15 and the shaft 4 through a hollow 4b in the shaft 4. As the lubrication oil and the refrigerant are mixed in a process of refrigerant circulation, and discharged to outside of the compressor, there is an accumulator 30 provided on the suction pipe 16 side of the compressor for separating and recovering the lubrication oil.
The operation of the related art rotary compressor will be explained with reference to FIGS. 1 and 2.
Upon starting the rotary compressor, the rotor 3 of the motor is rotated, to rotate the eccentric portion 4a of the shaft, eccentrically rotating the roller 12 inside of the cylinder 11 in a state the roller 12 is in contact with the vane 13. The eccentric rotation of the roller 12 reduces a volume of the compression chamber `C`, compressing low pressure refrigerant flowed into the compression chamber `C` through the suction pipe 16 to a required pressure. Following operation of the valve, the compressed high pressure refrigerant is discharged into the muffler 20 above the main bearing 14 through the cylinder discharge opening 11a and the discharge passage 14b in the main bearing. The high pressure refrigerant thus discharged into the muffler 20 is discharged outside of the muffler 20 through the muffler discharge opening 21. And, the high pressure refrigerant discharged outside of the muffler 20 is discharged outside of the rotary compressor through the discharge pipe 5 on top of the case 1 through gaps between the rotor 3 and the stator 2 or the case 1 and the stator 2. And, the high pressure refrigerant discharged outside of the compressor through the discharge pipe 5 is circulated through a refrigerating cycle to flow into the compressor again through the suction pipe 16.
However, the related art rotary compressor has the following problems.
First, because a pressure fluctuation and a kinetic turbulent energy contained in the compressed refrigerant is discharged without being consumed fully, noise can not be attenuated, effectively. And, a size of noise generation is directional depending on a position of a muffler discharge opening formed in the muffler. Moreover, the related art muffler has a limitation in attenuating the noise for a large sized compressor because the pressure fluctuation of the compressed refrigerant is substantial.
Second, since the hollow in the shaft merely serves in supplying lubricating oil to the main bearing and the supplementary bearing, and the lubricating oil supply fully depends on the pump, an overall compressor efficiency is dropped.
Third, because the high pressure refrigerant compressed in the compression chamber flows into the muffler through a discharge passage formed in one side of the main bearing, exerting an eccentric load to the shaft, a lifetime of the shaft is shortened.